The present invention relates to roof top drag reducing devices for land vehicles, particularly tractor-trailer trucks. The invention more specifically relates to adjustable drag reducing fairings mounted to the roofs of trucks which drive trailers to facilitate multi-shipments of trucks alone after the drag reducing fairings have been mounted to the truck roofs.
Roof top drag reducing devices including air fairings have come into widespread use on trucks, particularly on cabs pulling semi-trailers. These drag reducing devices direct the air passing over the top of the truck in such a way that the resistance of wind hitting the flat front portion of the trailer being pulled by the cab is minimized. Among other things, the drag reducing devices save fuel costs for the trucker. A fuller explanation and description of the general nature of drag reduction fairings and the advantages thereof may be found by reference to U.S. Pat. No. 4,245,862 issued on Jan. 20, 1981, the disclosure of which is expressly incorporated by reference herein.
U.S. Pat. Nos. 4,784,424 and 4,919,472, the disclosures of each of these patents being expressly incorporated by reference herein, describe a two-piece air resistance reduction fairing mounted to the roof of a truck to which a trailer is removably mountable. The air reduction device described in these two patents includes a lower, generally open base portion fixedly mounted to the roof of the cab, and an upper portion movably mounted relative to the fixed lower portion. The upper portion is selectively receivable within the fixedly mounted lower base portion in a first non-operational storage position, and is selectively movable into a position atop the fixed lower base portion in a second raised operational position. The upper fairing portion will be in its raised operational position when the truck is pulling a trailer and reduction of air resistance is desired. The upper fairing portion will be in its lowered storage position received within the fixed upper portion when reduction of air resistance is unnecessary, as for example, during multi-shipments of several trucks having the drag reducing devices mounted on the roofs thereof.
As more fully discussed in the aforementioned U.S. Pat. Nos. 4,919,472 and 4,784,424, the adjustable fairing reduces the maximum elevation of the trucks during multi-shipments to enable a plurality of such trucks to be shipped and transported in one operation by permitting towed or "piggy backed" trucks to fit under bridges and other overhead highway structures. In this manner, the drag reduction devices may be fully installed on the trucks by the truck manufacturer, the fairings and the trucks can be painted simultaneously, and thereafter delivered to a dealer in a substantially operational condition. This procedure reduces the overall costs and labor of installation and delivery of trucks with drag reduction devices mounted thereon. As also discussed in the aforementioned patents, a height adjustable air resistance reduction fairing advantageously permits conventional towing of a truck having a fairing installed thereon without requiring the removal of the fairing, but instead, by merely moving the top fairing portion into its lower non-operational position received within the lower opened base fairing portion fixedly mounted to the truck roof.
The aforementioned patents do not enable use of the base portion of the fairing as the roof of a sleeper compartment or sleeper space since the upper fairing section folds into the base and the base must be an opened structure.
U.S. Pat. No. 4,775,179 issued Oct. 4, 1988, discloses a cab of a tractor-trailer truck carrying a sleeper compartment having an elevated roof configured as a fairing. The fairing and the roof are joined together and the fairing itself thus comprises a single, non-adjustable piece. The height of the fairing remains constant, and the fairing may only be removed from the cab by completely removing the roof of the sleeper compartment or the entire sleeper compartment.
It is the primary object of the present invention to provide an improved drag reduction fairing of the type carried on the roof of a tractor-trailer truck, and being selectively adjustable between operational and non-operational positions. It is a further object of the present invention to provide an improved adjustable roof fairing of the aforementioned type in combination with a sleeper compartment also carried by or comprising part of the truck. Further objects and advantages of the present improvement will become apparent from the following description.